Method for fabricating a gate dielectric of a field effect transistor

Abstract

A method for fabricating a gate dielectric of a field effect transistor is disclosed herein. In one embodiment, the method includes the steps of removing a native oxide layer, forming an oxide layer, forming a gate dielectric layer over the oxide layer, oxidizing the gate dielectric layer, and annealing the layers and underlying thermal oxide/silicon interface. Optionally, the oxide layer may be nitridized prior to forming the gate dielectric layer. Optionally, the gate dielectric layer may be nitridized prior to oxidizing the gate dielectric layer. In one embodiment, at least portions of the method are performed using processing reactors arranged on a cluster tool.

1. A method for fabricating a gate dielectric of a field effect transistor, comprising:
 (a) providing a silicon substrate; 
 (b) removing a native oxide layer from the silicon substrate; 
 (c) forming an oxide layer on the silicon substrate, wherein the oxide layer is formed in a plasma process comprising exposing the oxide layer to a plasma comprising at least one of oxygen, nitric oxide, or nitrous oxide; 
 (d) forming a gate dielectric layer on the oxide layer; 
 (e) oxidizing at least a portion of the gate dielectric layer using an oxygen-containing plasma; and 
 (f) annealing the gate dielectric layer, the oxide layer, and interface between the oxide layer and the silicon substrate; 
 wherein the silicon substrate is maintained in a vacuum environment between steps (c) through (e). 
 
     
     
       2. The method of  claim 1 , further comprising:
 maintaining the silicon substrate in a vacuum environment from step (c) through step (f). 
 
     
     
       3. The method of  claim 1 , wherein step (b) further comprises:
 exposing the substrate to a solution comprising hydrogen fluoride and deionized water. 
 
     
     
       4. The method of  claim 1 , wherein step (c) further comprises:
 forming the oxide layer to a thickness between about 2-10 Angstroms. 
 
     
     
       5. The method of  claim 1 , wherein the plasma further comprises at least one of nitrogen, argon, or helium. 
     
     
       6. The method of  claim 1 , wherein step (c) further comprises:
 nitridizing the oxide layer. 
 
     
     
       7. The method of  claim 6 , wherein the step of nitridizing further comprises:
 creating a sub-layer of nitridized material in the oxide layer having a thickness between about 0.5-5 Angstroms. 
 
     
     
       8. The method of  claim 6 , wherein the step of nitridizing further comprises:
 creating a sub-layer of nitridized material in the oxide layer having a thickness between about 1-3 Angstroms. 
 
     
     
       9. The method of  claim 6 , wherein the nitridizing step further comprises:
 exposing the oxide layer to nitrogen-containing plasma. 
 
     
     
       10. The method of  claim 9 , wherein the nitrogen-containing plasma further comprises at least one of argon or helium. 
     
     
       11. The method of  claim 6 , wherein the nitridizing step further comprises:
 thermally nitridizing the oxide layer in an atmosphere comprising ammonia. 
 
     
     
       12. The method of  claim 11 , wherein the atmosphere further comprises at least one of nitrogen, helium, or argon. 
     
     
       13. The method of  claim 1 , wherein step (d) further comprises:
 forming the gate dielectric layer from at least one of silicon nitride, hafnium oxide, and hafnium silicate. 
 
     
     
       14. The method of  claim 13 , wherein step (d) further comprises:
 forming the gate dielectric layer from at least one of hafnium oxide or hafnium silicate to a thickness of about 10-60 Angstroms. 
 
     
     
       15. The method of  claim 13 , further comprising:
 forming the gate dielectric layer from silicon nitride to a thickness of about 2-10 Angstroms. 
 
     
     
       16. The method of  claim 1 , wherein step (d) further comprises:
 nitridizing the gate dielectric layer. 
 
     
     
       17. The method of  claim 16 , wherein the nitridizing step further comprises:
 exposing the gate dielectric layer to nitrogen-containing plasma. 
 
     
     
       18. The method of  claim 17 , wherein the nitrogen-containing plasma further comprises at least one of argon or helium. 
     
     
       19. The method of  claim 16 , wherein the nitridizing step further comprises:
 thermally nitridizing the gate dielectric layer in an atmosphere comprising ammonia. 
 
     
     
       20. The method of  claim 19 , wherein the atmosphere further comprises at least one of nitrogen, helium, or argon. 
     
     
       21. The method of  claim 1 , wherein step (e) further comprises:
 using a plasma of an oxygen-containing gas. 
 
     
     
       22. The method of  claim 21 , wherein the oxygen-containing gas comprises at least one of oxygen, nitric oxide, and nitrous oxide. 
     
     
       23. The method of  claim 21 , wherein the plasma further comprises at least one of nitrogen, helium, and argon. 
     
     
       24. The method of  claim 1 , wherein step (e) further comprises forming a plasma using a low energy plasma source. 
     
     
       25. The method of  claim 1 , wherein step (f) further comprises:
 thermally annealing the substrate in a rapid thermal processing chamber or a furnace. 
 
     
     
       26. A method for fabricating a gate dielectric of a field effect transistor, comprising:
 (a) providing a silicon substrate; 
 (b) removing a native oxide layer from the silicon substrate; 
 (c) forming an oxide layer on the silicon substrate; 
 (d) forming a gate dielectric layer on the oxide layer; 
 (e) oxidizing at least a portion of the gate dielectric layer using an oxygen-containing plasma, wherein oxidizing at least a portion of the gate dielectric layer further comprises forming in an upper portion of the gate dielectric layer an oxidized sub-layer having a thickness of about 0.2-10 Angstroms; and 
 (f) annealing the gate dielectric layer, the oxide layer, and interface between the oxide layer and the silicon substrate; 
 wherein the silicon substrate is maintained in a vacuum environment between steps (c) through (e). 
 
     
     
       27. The method of  claim 26 , wherein step (e) further comprises:
 forming the oxidized sub-layer to a thickness of about 0.5-5 Angstroms. 
 
     
     
       28. A method for fabricating a gate dielectric of a field effect transistor upon a substrate, comprising:
 (a) removing a native oxide layer from the substrate and placing the substrate in a nitrogen purged or vacuum environment; 
 (b) forming a thermal oxide layer on the substrate; 
 (c) forming a gate dielectric layer on the thermal oxide layer; 
 (d) oxidizing at least a portion of the gate dielectric layer using an oxygen-containing plasma; 
 (e) thermally annealing the substrate having the thermal oxide layer and the oxidized gate dielectric layer formed thereon; and 
 (f) nitridizing the thermal oxide layer prior to step (c). 
 
     
     
       29. A method for fabricating a gate dielectric of a field effect transistor upon a substrate, comprising:
 (a) removing a native oxide layer from the substrate and placing the substrate in a nitrogen purged or vacuum environment; 
 (b) forming a thermal oxide layer on the substrate; 
 (c) forming a gate dielectric layer on the thermal oxide layer; 
 (d) oxidizing at least a portion of the gate dielectric layer using an oxygen-containing plasma; 
 (e) thermally annealing the substrate having the thermal oxide layer and the oxidized gate dielectric layer formed thereon; and 
 (f) nitridizing the gate dielectric layer prior to step (d). 
 
     
     
       30. A method for fabricating a gate dielectric of a field effect transistor, comprising:
 (a) providing a silicon substrate; 
 (b) removing a native oxide layer from the silicon substrate; 
 (c) forming an oxide layer on the silicon substrate; 
 (d) forming a gate dielectric layer on the oxide layer; 
 (e) oxidizing at least a portion of the gate dielectric layer using an oxygen-containing plasma; 
 (f) annealing the gate dielectric layer, the oxide layer, and interface between the oxide layer and the silicon substrate; and 
 (g) nitridizing at least one of the oxide layer formed in step (c) or the gate dielectric layer formed in step (d). 
 
     
     
       31. The method of  claim 30 , wherein the step of nitridizing further comprises:
 creating a sub-layer of nitridized material in at least one of the oxide layer or the gate dielectric layer having a thickness between about 0.5-5 Angstroms. 
 
     
     
       32. The method of  claim 30 , wherein the step of nitridizing further comprises:
 creating a sub-layer of nitridized material in at least one of the oxide layer or the gate dielectric layer having a thickness between about 1-3 Angstroms. 
 
     
     
       33. The method of  claim 30 , wherein the nitridizing step further comprises:
 exposing at least one of the oxide layer or the gate dielectric layer to a nitrogen-containing plasma. 
 
     
     
       34. The method of  claim 33 , wherein the nitrogen-containing plasma further comprises at least one of argon or helium. 
     
     
       35. The method of  claim 30 , wherein the nitridizing step further comprises:
 thermally nitridizing at least one of the oxide layer or the gate dielectric layer in an atmosphere comprising ammonia. 
 
     
     
       36. The method of  claim 35 , wherein the atmosphere further comprises at least one of nitrogen, helium, or argon.